A prototype analog scintigraphic imaging system has been developed for use in small animal imaging studies. Unlike conventional scintillation cameras, this system uses a single position-sensitive photomultiplier tube (PMT) to determine the location of scintillation events within the sodium iodide scintillator. Performance measurements and imaging studies in small animals confirm the ability of this system to obtain high-resolution images of the lungs, heart, brain, and other structures in animals the size of rats and guinea pigs. The camera is coupled to a commercial software/hardware package, running on a Macintosh computer system that permits all common forms of nuclear medicine acquisition/ processing procedures routinely utilized in human studies to be performed on small animals. The instrument developed is a low-cost, low-linearity system. Work during this project period has focused on an evaluation of a low-cost, special-purpose, improved linearity system. At present, this proposed system will input a linear pulse to a flash or Sigma-Delta ADC. Position and energy information will then be input to either a DSP board within an embedded computer, into an EPROM/FPGA logic design, or to a stand-alone computer. The optimized output from this system will then be directed to the Macintosh through a video DAC.